Dan: To prevent the "slug " effect, cut slits in the front of the cups, about 1/2 Inch long, so that you create "tabs" that fold out as the packet leaves the muzzle and act as air brakes for the shot cups. This is one time where mimicking what the factories have been doing since they introduced plastic shotcups for modern cartridges makes sense. I have no doubt that a properly constructed shotcup will work in any choked gun barrel. In a cylinder bore, however, the diameter of the cup, as to be a couple of hundred thousandths under bore diameter, and those slits help to get the cup to separate from the shot.
Roundball's success using a " tail" on the back of the cups he makes, also works. No, I would not use them for shooting at geese, but for turkey, where you are only likely to get one shot per bird, they make sense.
He ties a knot in a string, which goes through the center of the bottom of his paper cup, with the bottom glued shut. The string holds a cotton strip, tied with another knot, but with a couple of inches of string so that it follows well behind the cup. The cotton strip becomes the air brake, slowing and separating the cup from the shot after the package leaves the muzzle.
In loading, the cotton tail is folded and stuffed down the barrel after an OP Wad and cushion wad are seated. The String follows, and the cup is entered into the muzzle. Then the shot is loaded into the cup, the rest of the cup is finger pressed into the muzzle, followed by a OS card( or two) and the entire shot package is pushed down onto the Cushion wad.
I like the idea of using newspaper, as its so available to all of us, and represents what I think the value that most newspaper reporting has sunk to these days. But the diameter of the tube has to be less than the bore diameter, and you have to experiment some to find out how many wraps around your mandrill are needed to create a cup that won't become confetti when it leaves the muzzle.
Some members here have no problem Tying the shot into the packet, at both ends. They claim that it splits open and produces good groups. I have not tried their systems, so can't comment. I believe you would get more reliable patterns and more consistent separation of the shot from the newspaper if you tear the front end of the shot packet OFF at the muzzle, and put an OS card or two on top to hold the shot in your barrel. You might also have to cut slits into the newsprint package, 1/4-1/2", but I have not heard of others having to do this.
[ I have made cups from the 3M "post-it Note" paper, with the glue strip on the top to use to seal the tube I make. That paper is substantially thicker than newsprint, and I need the slits in the cups to make them separate reliably. I did get low modified patterns from my cylinder bore shotgun barrel when using these paper shotcups.]
Keep experimenting, and good luck during this SPring's Turkey season. :thumbsup:
